The Flaviviridae are a family of positive, single-stranded, enveloped RNA viruses. They are found in arthropods, primarily ticks and mosquitoes, and can occasionally infect humans. Members of this family belong to a single genus, Flavivirus, and cause widespread morbidity and mortality throughout the world. Some of the mosquitoes-transmitted viruses include: Yellow Fever, Dengue Fever, Japanese encephalitis, and West Nile viruses. Other Flaviviruses are transmitted by ticks and are responsible of encephalitis and hemorrhagic diseases: Tick-borne Encephalitis (TBE), Kyasanur Forest Disease (KFD) and Al-Khurma disease, and Omsk hemorrhagic fever.
With incidence rates on the rise, worldwide dengue epidemics have become a major public health concern not only for those living in the tropics, but in Central America and the U.S. as well.
The successful yellow fever 17D vaccine, introduced in 1937, produced dramatic reductions in epidemic activity. Effective killed Japanese encephalitis and Tick-borne encephalitis vaccines were introduced in the middle of the 20th century. Unacceptable adverse events have prompted change from a mouse-brain killed Japanese encephalitis vaccine to safer and more effective second generation Japanese encephalitis vaccines. These may come into wide use to effectively prevent this severe disease in the huge populations of Asia—North, South and Southeast. The dengue viruses produce many millions of infections annually due to transmission by a successful global mosquito vector. As mosquito control has failed, several dengue vaccines are in varying stages of development. However, additional vaccines and other therapeutics against pathogenic Flaviviridae are needed.